Photo-generated high-energy surface states can help to produce chlorine in aqueous environments. Here, aligned rutile (TiO 2) nanocrystal arrays are grown onto fluorine-doped tin oxide (FTO) substrates and activated either by hydrothermal Sr/Ba surface doping and/or by vacuum-annealing. With vacuum-annealing, highly photoactive films are obtained with photocurrents of typically 8 mA cm −2 at 1.0 V vs. SCE in 1 M KCl (LED illumination with λ = 385 nm and approx. 100 mW cm −2). Photoelectrochemical chlorine production is demonstrated at proof-of-concept scale in 4 M NaCl and suggested to be linked mainly to the production of Ti(III) surface species by vacuum-annealing, as detected by post-catalysis XPS, rather than to Sr/Ba doping at the rutile surface. The vacuum-annealing treatment is proposed to beneficially affect (i) bulk semiconductor TiO 2 nanocrystal properties and electron harvesting, (ii) surface TiO 2 reactivity towards chloride adsorption and oxidation, and (iii) FTO substrate performance. [Figure not available: see fulltext.].

Original languageEnglish
Pages (from-to)65-77
Number of pages13
Issue number1
Early online date9 Nov 2020
Publication statusPublished - 31 Jan 2021


  • Brine
  • Disinfection
  • Field effects
  • Hydrothermal growth
  • Oxygen vacancies
  • Solar energy

ASJC Scopus subject areas

  • Electrochemistry


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